Abstract : A parallel plate electrostatic analyzer (ESA) to detect 0.08 to 17 keV electrons was launched on the S3-2 satellite in late 1975. Analysis of the low altitude data revealed that the ESA was responding to the neutral atmosphere through a ram effect. The ram effect was confined to attack angles of less than about 30 deg, and was generally present only at the lowest altitudes (250-300 km). By excluding all data with an ESA attack angle of less than 45 deg, completely reliable electron spectra are obtained at all altitudes. (Author)